A team of researchers has developed a new at-home, saliva-based Covid-19 testing platform that can detect Covid-causing virus with the same level of sensitivity as PCR test in just 45 minutes.
The study, published in the journal ACS Sensors, says the team developed a palm-sized testing kit, where an individual spits into a cartridge and inserts it into the processing platform. Within 45 minutes, test results are sent to a custom Android app developed by the researchers.
"PCR test results take about an hour to develop in a lab, but you have to factor in the time it takes to send the sample to a lab and for the lab to process it," said principal investigator Weihua Guan, associate professor at Penn State University in the US.
"We wanted to create a viable alternative to the PCR for people to use at home, without having to endure the invasive nasal test," Guan added.
The platform uses reverse transcription loop-mediated isothermal amplification, or RT-LAMP to detect the virus.
The testing device first heats the saliva to 203 degrees Fahrenheit, the temperature at which viral particle shells break apart and release their genetic material. The genetic material is then mixed with pre-packaged reagents in a microfluidic cartridge.
Finally, the sample is cooled to 149 degrees Fahrenheit, triggering another chemical reaction in which a few viral molecules are multiplied into billions of copies, making the virus easier to identify. If the virus is present in the saliva sample, the user will receive a positive result on their connected smartphone app.
To test the setup, they infused human saliva samples purchased commercially with inactivated SARS-CoV-2 virus particles and ran the samples through the prototype. They also tested a couple of clinical specimens. The platform accurately determined whether every sample was positive or negative for the virus.